Exploring The Planets - Asteroids

Gaspra
33k JPEG NASA Press Release #P-40450	In October, 1991, the first close-up views of the asteroid Gaspra were taken by the Galileo spacecraft on its way to Jupiter. Gaspra is an irregularly shaped body 19 by 12 by 11 kilometers (12 by 7.5 by 7 miles) whose rocky surface is covered with impact craters. The minor color differences in this enhanced image show subtle variations due to surface texture and possibly composition.

Ida and Dactyl
The Galileo spacecraft also encountered the asteroid Ida. Close inspection of the image data revealed a small object - believed to be a satellite orbiting Ida. Ida's moon was named Dactyl. Ida is roughly 58 by 23 kilometers (36 by 14 miles) and Dactyl is about 1.2 by 1.4 by 1.6 kilometers (.74 by .87 by .99 miles).	22k JPEG NASA Press Release #P-43731

Phobos and Deimos

Mars has two known moons, Phobos and Deimos, that may be asteroids that were captured by the planet's gravitational field.

151k GIF
NASA Press Release #P-76-H-729

Close up view of Phobos' surface. Phobos is ellipsoid in shape, 27 by 21 by 19 kilometers (17 by 13 by 12 miles). The origin of the conspicuous, parallel grooves is not yet understood.

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NASA Press Release #P-77-HC-58 / VO 428B22.

Deimos is an ellipsoid similar to Phobos and measures 15 by 12 by 11 kilometers (9 by 7.5 by 7 miles).

A Comparison
This image shows the relative size differences between asteroid 951 Gaspra (top) and Mars' satellites Deimos (lower left) and Phobos (lower right). The Gaspra image was taken in 1991 by the Galileo spacecraft, and the Phobos and Deimos images were taken by the Viking Orbiter spacecraft in 1977.	82k JPEG NASA Press Release #41382

Ceres
This computer-enhanced image of Ceres was collected by the Hubble Space Telescope in 2004.	43k JPEG STScI-PRC05- 27b, NASA, ESA, and J. Parker (Southwest Research Institute)